1. Technical Field
The present invention generally relates to a mounting structure for an electrical unit of a vehicle. More specifically, the present invention relates to a vehicle structure having a mounting structure that secures an electrical unit that emits a large amount of heat in an area that is well cooled.
2. Description of Related Art
In recent years, in order to improve exhaust purification performance and fuel economy, it is becoming common for gasoline engines and other spark ignition engines to inject the fuel into the combustion chamber during the compression stroke. A layer-like stratified air-fuel mixture is formed that comprises air-fuel mixtures of combustible mixture ratios that can be ignited around the spark plug so as to conduct combustion (stratified combustion) at an extremely lean air-fuel ratio (an air-fuel ratio in the vicinity of the lean limit). Japanese Laid-Open Patent Publication Nos. 62-191622 and 2-169834 disclose engines that utilize direct injection of the fuel into the combustion chamber during the compression stroke.
In such direct injection engines, electromagnetic drive fuel injection valves are often used to inject fuel into the combustion chamber during the compression stroke. The electromagnetic drive fuel injection valves consume a large amount of electric power because the fuel is injected at a high pressure during the compression stroke. Consequently, the electronic drive circuit or unit that drives the fuel injection valves supplies a large amount of power and emits a large amount of heat.
Japanese Laid-Open Patent Publication No. 11-294289 discloses mounting the drive unit of an electromagnetic drive fuel injection valve to the exhaust manifold on the upper part of an engine. Since the drive unit is mounted on the high-temperature exhaust manifold, a separate cooling device is needed for the drive unit. The cooling device has cooling fins that need to be mounted so that the cooling fins are aimed upward on the side opposite of the exhaust manifold. Therefore, an even larger space is required for mounting an engine cover over the exhaust manifold and the cooling device. Furthermore, since the cooling fin structure requires air to pass over the cooling fins, it is also necessary to install the air guide structure.
In view of the above, there exists a need for an improved mounting structure for installing an electrical unit that emits a large amount of emitted heat. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.